Megan's mother, 63-year-old Margaret Smith, was taken to the hospital because of rapidly declining health. She had been battling liver cancer for a year and was too sick to survive a transplant.

A nurse, Olivia Neufelder, comforted Margaret by singing her favorite song, “Dancing in the Sky” by Dani and Lizzy.

Megan posted the emotional video to Facebook, writing that Olivia never left Margaret's side. They sat together for hours as the anesthesia wore off.

"Words cannot describe the appreciation and love we feel for nurse Olivia who mom calls her angel," she wrote on Monday. "Your dedication to your patients is beyond any that I have seen, you truly are a beam of light and I cannot thank you enough for the compassion and care and love you shared for my mother."

Margaret was moved to a nursing home where she passed away on Wednesday.

The video has been viewed nearly 3.5 million times.

Olivia Neufelder told NewsChannel 5 that Margaret "didn't feel like a patient at that time."

"I recently lost my grandmother and went through a similar experience and I was singing to her as she passed too. Margaret really has helped me more than she knows," Neufelder said.

Margaret Smith leaves behind a daughter and son. A GoFundMe account has been set up to help with funeral expenses.